The Forest Department has launched an investigation to assess how much damage a sunken coal-laden ship in the river Pashur might cause the Sundarbans, as environmentalists predict the disastrous impact on the mangroves.

MV Bilash, a lighter vessel with 775 tonnes of coal, sank in Harbarhia area, around 60 nautical miles from the Mongla Port, in the Sundarbans' Chandpai Range around 3am on Sunday.

The port authorities and importers, however, claim the sunken ship has not created any environmental threat.

Sundarban Eastern Divisional Forest Officer Mahmudul Hasan told bdnews24.com later in the night that they tasked Assistant Conservator of Forest Md Shaheen Kabir to look into how much damage the coal in the sunken ship can cause to the Sundarbans.

Md Lalon Howladar, manager (operations) at Sahara Enterprise that imported the coal said that MV Bilash received 775 metric tonnes from another vessel and set off for Dhaka’s Mirpur. According to him, MV Bilash had the carrying capacity of 1,000 metric tonnes.

The lighter vessel then ran aground on a sand bar in the Harbaria area. The crew contacted the port for help, but by the time help arrived strong tides had put the vessel upside down.

The coal was still inside the vessel so there was no concern about any environmental disaster, claims Sahara Enterprise.

According to Harbour Master Walimullah the MV Shipsha was sent to the location to try and rescue the MV Bilash, but the tides overturned the hip around 3am and caused it to sink.

Parts of the lighter ship are still visible and recovery operations are going on, he said.

Forest Department Assistant Director Md Emdadul Haque told bdnews24.com they would send a team to the site on Monday morning to collect samples of the water and coal for tests.

He said the sulphur mixed in the coal could cause environmental damage if it is released in a blocked area, but in open water, the sulphur can spread and cause little harm.